1. Technical Field
This invention relates in general to integrated circuits and, more particularly, to managing power in a processor.
2. Description of the Related Art
For many years, the focus of processor design, including designs for microprocessor units (MPUs), co-processors and digital signal processors (DSPs), has been to increase the speed and functionality of the processor. Presently, power consumption has become a serious issue. Importantly, maintaining low power consumption, without seriously impairing speed and functionality, has moved to the forefront in many designs. Power consumption has become important in many applications because many systems, such as smart phones, cellular phones, PDAs (personal digital assistants), and handheld computers operate from a relatively small battery. It is desirable to maximize the battery life in these systems, since it is inconvenient to recharge the batteries after short intervals.
Currently, approaches to minimizing power consumption involve static power management; i.e., designing circuits which use less power. In some cases, dynamic actions have been taken, such as reducing clock speeds or disabling circuitry during idle periods.
While these changes have been important, it is necessary to continuously improve power management, especially in systems where size and, hence, battery size, is important to the convenience of using a device.
In addition to overall power savings, in a complex processing environment, the ability to dissipate heat from the integrated circuit becomes a factor. An integrated circuit will be designed to dissipate a certain amount of heat. If tasks require multiple systems on the integrated circuit to draw high levels of current, it is possible that the circuit will overheat, causing system failure.
In the future, applications executed by integrated circuits will be more complex and will likely involve multiprocessing by multiple processors, including MPUs, DSPs, coprocessors and DMA channels in a single integrated circuit (hereinafter, a “distributed processing system”). DSPs will evolve to support multiple, concurrent applications, some of which will not be dedicated to a specific DSP platform, but will be loaded from a global network such as the Internet. Accordingly, the tasks that a distributed processing system will be able to handle without overheating will become uncertain.
Accordingly, a need has arisen for a method and apparatus for managing power in a circuit without seriously impacting performance.